Device for tensioning a flexible band

ABSTRACT

A device ( 17 ) is provided for tensioning a flexible band ( 3 ) used to maintain a bone element on an implant. The device includes a rod ( 18 ) having a first end ( 19 ) provided with means ( 20 ) for bearing on the implant, a movable part ( 32 ) for hooking the flexible band onto a portion ( 28 ) of the device, and means ( 34 ) for adjustably locking the movable part in translation in relation to the portion of the device. The rod ( 18 ) includes a gripping handle ( 26 ) at the second end ( 27 ) thereof. The aforementioned portion of the device forms an angle α with the rod ( 18 ) to which it is rigidly connected at an intermediary point, the direction of the band being altered at an angle, and the aforementioned adjustable locking means ( 34 ) includes manual screwing means ( 35 ) for actuating the movable part.

CROSS REFERENCE TO RELATED APPLICATION

This application is a continuation of co-pending InternationalApplication No. PCT/FR2011/000639, filed Dec. 6, 2011, the contents ofwhich are hereby incorporated by reference in their entirety.

BACKGROUND OF THE INVENTION

The present invention relates to a device for tensioning a flexiblestrip for securing a bony element to an implant, comprising a rod havinga first end provided with means for bearing on the implant, a mobilepart for attaching the flexible strip to a portion of the device andadjustable means for blocking the part that is mobile in translationrelative to said portion of the device.

It is particularly importantly applicable, although not exclusivelyapplicable, to the field of the straightening of the spinal column of apatient having abnormal curvature.

In this case, with the vertebrae not being correctly aligned relative toone another in relation to the vertebral axis, they exhibit mutualinclinations.

In order to straighten the assembly, it is known to reset the lateraledges of the vertebrae to a substantially equivalent distance, on allsides of the spinal column, by the use of rods linking together eitherare screws, that are inserted into the vertebrae themselves, or hooksthat are introduced along the vertebral canal.

However, such devices present drawbacks because they are aggressive.

To mitigate these drawbacks, there has been proposed a flexible link forfixing the vertebra to the link part which is in turn fixed to thestraightening rod.

Means for blocking the flexible link by reclosing the link part on therod are then necessary.

The problem that the invention seeks to resolve is in this case that ofthe tensioning of this flexible link for fixing the vertebra to the linkpart.

In practice, it is important for the user, when fitting this link, to beable to gradually retighten the latter without in any way damaging thebony element which is then compressed by the flexible strip.

There are currently tensioning ancillaries provided with a rod, a partthat is mobile in translation along the rod and an element mounted onthe mobile part tending horizontally to separate the end of the rod fromthe part.

Such an ancillary does, however, present drawbacks.

It in fact entails pulling in the extension of the link itself which hasto be twisted to be able to allow it to be tensioned.

Furthermore, no manual feedback of the tension is possible with such aninstrument which thus requires, to avoid crushing the bony element, anadjustable dynamometric system making it possible to stop the tensioningbeyond a certain determined value.

SUMMARY OF SELECTED INVENTIVE ASPECTS

The present invention aims to provide a device for tensioning a flexibleband that provides a better response than those previously known to therequirements of the practice, notably in that it will allow for a muchgreater flexibility, a better sensitivity to the degree of tensioningbecause of the very design of the tools used for such a tensioning, andin that it presents much improved and simple adjustment possibilities.

To this end, in an aspect, the invention notably proposes a device fortensioning a flexible strip for securing a bony element to an implant,comprising a rod having a first end provided with means for bearing onthe implant, a mobile part for attaching the flexible strip to a portionof the device and adjustable means for blocking the part that is mobilein translation relative to said portion of the device, characterized inthat the rod comprises a gripping sleeve at its second end, in that saidportion of the device forms an angle with the rod to which it is rigidlyfixed at an intermediate level with angular return of the strip and inthat the adjustable blocking means comprise manual screwing meansspecifically for actuating the mobile part.

The manual screwing means for actuating the mobile part which is itselfoffset on a lateral branch forming an angle, allow for a gradual andcontrolled tensioning of the flexible strip.

In advantageous embodiments, there is also recourse to one and/or otherof the following arrangements:

-   -   the adjustable blocking means comprise a rack securely attached        to the portion of the device, and the screwing means comprise a        non-return ratchet system with actuation key securely attached        to the mobile part.

The actuation key allows for a good manual tightening sensitivity;

-   -   the ratchet system comprises a lever arm for releasing the        ratchet. It is therefore very easy to release the tension, for        example to allow for a new adjustment;    -   the screwing means comprise at least one wing screw;    -   the device comprises a link part between rod and device portion        formed by a block provided with two sprocket wheels with        mutually parallel axes for angular return of said strip in its        plane, said block being securely attached to said rod;    -   the link part is mobile along the rod;    -   the attachment of the strip to the mobile part comprises a        sprocket wheel of axis parallel to those of the sprocket wheels        of the block;    -   the angle of said portion of the device relative to the rod is        adjustable;    -   the angle α of said portion of the device relative to the rod is        between 90° and 130°;    -   the angle α of said portion of the device relative to the rod is        90°.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be better understood from reading the followingdescription of an embodiment given as a nonlimiting example. Thedescription refers to the accompanying drawings in which:

FIG. 1 is a perspective view of the flexible strip for securing a bonyelement to an implant by the use of a fixing body on said implant.

FIG. 2 is a bottom view of a vertebra showing the fixing body on the rodand the flexible strip for linking the vertebra with the fixing body.

FIG. 3 is a side view of the device according to the embodiment of theinvention which is more particularly described here.

FIG. 4 is an axionometric perspective view of the device of FIG. 3.

FIG. 5 is a cross-sectional view of the mobile part and of theadjustable blocking means according to the embodiment of the inventionwhich is more particularly described here.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS

Hereinafter in the description, the same reference numbers will be usedto designate the same elements.

FIG. 1 shows an embodiment of a fixing body 1 on a cylindrical rod 2 anda flexible strip 3 made of braided polymer, for example polyester, 6 mmwide and 30 cm long to form the loop 4.

Adjustable means 5 for blocking the flexible strip on the fixing body 3are provided. The fixing body 1 is, for example, formed by a part whichis all one piece forming a clamp having U-shaped cross section, said Ucomprising two thick branches 6, 7 with a substantially demi-oval shapedcross section, symmetrical relative to a longitudinal plane and linkedtogether by a link part 8 in the form of a half toroidal ring forming,on one side, the demicylindrical bottom of the U and, on the other side,the rounded outer walls of the branches 6 and 7.

The bottom wall of the U is of a shape complementing that of the rod 2,or substantially complementing same.

Each branch 6, 7 includes a void 9, for example in the form of a wideslot, for example five to six times wider than the thickness of thebraid to facilitate its introduction during the operation.

Each branch 6 and 7 includes a cylindrical orifice for the passage ofthe blocking means 5, namely a bore of diameter D and a tappedcylindrical orifice for screwing of diameter d<D.

The blocking means 5 are formed by a link part 10, or screw, provided onone side with a head 11 for passing into the bore of the U and on theother side an end 12 for screwing into said facing tapped cylindricalorifice.

In the embodiment that is more particularly described here, the head ofthe screw 11 comprises a top cylindrical part and a bottomdownwardly-tapering part 13, arranged to compress the rod 2 as the partis screwed.

The flexible strip 3 is joined at its other ends 14 and 15 at 16 forexample by stitching, gluing or other means that are known per se.

FIG. 2 shows the vertebra V as fixed via the loop 4 to the rod 2 via thebody 1 to allow for the tensioning of the loop 4 on the bone V asrepresented in FIG. 2.

There now follows a description of the device 17 with reference to FIGS.3 and 4.

The device 17 for tensioning the flexible strip 3 via the loop 4therefore comprises a slender rod 18 that is for example 40 cm long andcylindrical, provided at a first end 19 with bearing means 20consisting, for example, of a part securely attached to the end 19having a part 21 in the form of cylindrical hooks, of a shapecomplementing and arranged to cooperate with the bar 2.

More specifically, the part 20 is, for example, formed by a heel part 22securely attached to the end 19 extended on each side by two parallelsymmetrical branches 23 provided at their ends with two shoulder parts24 arranged to cooperate with the rod 2.

The two branches 23 are themselves separated by an opening 25 into whichis inserted the body 1 for fixing to the bar in a manner that is knownper se.

The device includes a manual gripping sleeve 26 in the extension of therod 18 at its second end 27.

The device according to the embodiment of the invention that is moreparticularly described here also includes a portion 28 forming an angleα with the rod 18 to which it is rigidly fixed at an intermediate levelvia a link part 29 between rod and said portion, formed by a block thatis, for example, substantially parallelepipedal, provided with twosprocket wheels 30 and 31 with mutually parallel axes, perpendicular tothe axis of the rod 18, for angular return of the strip 3 in its plane,towards the rod portion 28.

There is provided a part 32 that is mobile in translation (arrow 33)relative to the portion 28.

This mobile part 32 comprises adjustable means 34 for blocking themobile part in its said translation, provided with screwing means 35.

Referring also to FIG. 5, the adjustable blocking means 34 comprise arack 36 securely attached to the portion 28, the screwing means 35comprising a non-return ratchet system 37 with actuation key 38 securelyattached to the mobile part.

More specifically, the adjustable blocking means comprise a body 39pierced with a bore 40 through which passes the end 41 of the portion 28which is fixed to the rod 18 by the link part 29.

The end 41 which includes on its top part the teeth 42 of the rack willcooperate by soft friction with the bore 40 of the part 39 whichincludes, in its top part, a snug 43 pierced with a lateral bore 44through which passes the axis 45 of the wings 46 for manually actuatinga toothed wheel 47 arranged to cooperate with the teeth 42 of the rack36 so that, when the wing screws are turned, the mobile part 39 will bedisplaced transversely along the rod.

Ratchet means 48, known per se, are designed to be able to be actuatedand unlocked when the non-return lever 49 is lifted, in a manner that isknown per se.

This makes it possible in practice to release the ratchet and to releasethe tension of the flexible strip as will now be described in moredetail.

In practice, the flexible strip, more precisely the ends of thisflexible strip abutting at 16 are securely attached to a third sprocketwheel 50 fixed to the end 51 of the mobile part, so that, when themobile part is displaced towards the outside of the rod, the strip 3 andthe loop 4 are tensioned.

In an advantageous embodiment, the angle α between the portion and therod is adjustable to be blocked in a manner that is known per se.

There now follows a description, with reference to FIGS. 2 and 3, of theoperation of a device according to the invention.

The user will first of all form the loop 4 around the bony element thenslide the ends of this loop through the body 1 which will then be fixedto the rod by closing the U of the part 1 via the fixing means 5 so thatthe branches of the flexible strip can then be slid through the orificesof the body 8.

The flexible strip is then joined at 16 at its ends by a closure systemthat is known per se and is then passed into the return sprocket wheelsor capstans 30, 31 and 50.

The dimensioning of the flexible strip will have been calculatedbeforehand so that the strip is almost in the tautened position. Shouldthe tension be greater, it is also possible to move, for example, in oneembodiment, the part for fixing the portion 28 to said rod so as toobtain the desired initial tension.

The tensioning is then effected by turning the wings 46, which drivesthe toothed wheel 47 which meshes with the rack.

The non-return function is provided by the lever which bears with theaid of a screw 52 on the teeth of the same rack.

The tension can be released by acting on the lever 49 in order to allowfor a return of the mobile part or carriage.

As is evident, and as also results from the foregoing, the presentinvention is not limited to the embodiments that are more particularlydescribed. On the contrary, it encompasses all the variants therefor andnotably those in which there is only a single wing key, that in whichthe screwing means are different and/or those in which the intermediateparts 29, 51 are formed differently.

The invention claimed is:
 1. A device for tensioning a flexible stripfor securing a bony element to an implant, comprising: a rod having afirst end provided with means for bearing on the implant; and a mobilepart moveable in translation along a portion of the device and ablocking device for blocking the mobile part in different translationalpositions on said portion of the device; wherein, the device comprises agrip in spaced relation to said portion of the device, said portion ofthe device forms an angle with the rod to which it is rigidly fixed toprovide an angular return of the strip along said portion of the device,and the blocking device comprises a manually turnable mechanism foractuating movement of the mobile part along said portion of the device.2. A device according to claim 1, wherein the blocking device comprisesa rack securely attached to the portion of the device, and the manuallyturnable mechanism comprises a non-return ratchet system.
 3. A deviceaccording to claim 2, wherein the ratchet system comprises a lever armfor releasing the ratchet.
 4. A device according to claim 1, wherein themanually turnable mechanism comprises at least one wing member.
 5. Adevice according to claim 1, further comprising a link part between therod and the portion of the device, said link part being formed by ablock provided with two wheels with mutually parallel axes for angularreturn of said strip along said portion of the device, said block beingsecurely attached to said rod.
 6. A device according to claim 5, whereinthe link part is moveable along the rod.
 7. A device according to claim6, wherein the mobile part further comprises a wheel having its axisparallel to those of the wheels of the block, for attachment of saidstrip.
 8. A device according to claim 5, wherein the mobile part furthercomprises a wheel having its axis parallel to those of the wheels of theblock, for attachment of said strip.
 9. A device according to claim 1,wherein an angle α of said portion of the device relative to the rod isadjustable.
 10. A device according to claim 1, wherein an angle α ofsaid portion of the device relative to the rod is between 90° and 130°.11. A device according to claim 10, wherein the angle α of said portionof the device relative to the rod is 90°.
 12. A device according toclaim 1, wherein said grip is provided separate from said manuallyturnable mechanism.
 13. A device according to claim 12, wherein saidgrip is connected at a second end of said rod opposite said first end.14. A device according to claim 1, wherein said manually turnablemechanism comprises a toothed wheel rotatably engaged with a rackaffixed to said portion of the device.
 15. A device according to claim1, wherein said portion of the device is rigidly affixed at anintermediate level to said rod.
 16. A device for tensioning a flexiblestrip for securing a bony element to an implant, comprising: a rodhaving a first end provided with means for bearing on the implant; and amobile part moveable in translation along a portion of the device and ablocking device for blocking the mobile part on said portion of thedevice; wherein, the device comprises a grip in spaced relation to saidportion of the device, said portion of the device forms an angle withthe rod to which it is rigidly fixed to provide an angular return of thestrip along said portion of the device, and the blocking devicecomprises a rack securely attached to the portion of the device, and amanually turnable mechanism for actuating movement of the mobile partalong said portion of the device, said manually turnable mechanismcomprising a non-return ratchet system.
 17. A device according to claim16, wherein the ratchet system comprises a lever arm for releasing theratchet.
 18. A device for tensioning a flexible strip for securing abony element to an implant, comprising: a rod having a first endprovided with means for bearing on the implant; and a mobile partmoveable in translation along a portion of the device and a blockingdevice for blocking the mobile part on said portion of the device;wherein, the device comprises a grip in spaced relation to said portionof the device, said portion of the device forms an angle with the rod towhich it is rigidly fixed to provide an angular return of the stripalong said portion of the device, and the blocking device comprises amanually turnable mechanism for actuating movement of the mobile partalong said portion of the device, said manually turnable mechanismcomprising a toothed wheel rotatably engaged with a rack affixed to saidportion of the device.